Observational, Multicenter Study of the Efficacy and Safety of Cervical Disk Arthroplasty With Mobi-C in the Treatment of Cervical Degenerative Disk Disease. Results at 10 years Follow-Up.

BACKGROUND: Cervical disk arthroplasty replacement (CDA) was developed to avoid specific disadvantages of cervical fusion. The purpose of this paper is to provide 10-year follow-up results of an ongoing prospective study after CDA. METHODS: Three hundred eighty-four patients treated using the Mobi-C (ZimVie, Troyes, France) were included in a prospective multicenter study. Routine clinical and radiologic examinations were reported preoperatively and postoperatively with up to 10-year follow-up. Complications and revision surgeries were also documented. RESULTS: At 10 years showed significant improvement in all clinical outcomes [Neck Disability Index, visual analog scale (VAS) for arm and neck pain, physical component summary of SF36, and mental component summary of SF36). Motion at the index level increased significantly over baseline (mean range of motion=7.6 vs. 8 degrees at five years and 6.0 degrees preoperatively; P <0.001) and 71.3% of the implanted segments remained mobile (range of motion>3 degrees). Adjacent disks were also mobile at 10 years with the same mobility as preoperatively. At 10 years, 20.9% of the implanted segments demonstrated no heterotopic ossification. Thirty-four patients (8.9%) experienced 41 adverse events, with or without reoperation during the first five years. We found only two additional surgeries after five years. We observed an increased percentage of working patients and a decrease in medication consumption. Regarding the overall outcome, 94% of patients were satisfied. CONCLUSIONS: Our 10-year results showed significant improvement in all clinical outcomes, with low rates of revision or failure. This experience in patients with long-term follow-up after CDA endorses durable, favorable outcomes in properly selected patients.

The influence of total disc arthroplasty with Mobidisc prosthesis on lumbar spine and pelvic parameters: a prospective in vivo biomechanical study with a minimum 3 year of follow-up.

BACKGROUND: This study examined the impact of Mobidisc implant on spinopelvic parameters, with particular focus on the preservation of the lumbar lordosis (LL) and on the segmental lordosis (SL) of the treated and adjacent segments. METHODS: A prospective study was conducted on 63 consecutive patients with symptomatic degenerative disc disease who underwent Mobidisc implantation at the Clinic for Spinal Diseases in Strasbourg, France. Based on the profile images of the whole, the following static spinopelvic parameters were measured and analysed: lumbar lordosis L1-S1 (LL), SL for L3-L4, L4-L5 and L5-S1, sacral slope (SS), pelvic tilt (PT) and pelvic incidence. In the lumbar spine images, the anterior (ADH) and posterior disc height (PDH) were measured prior to surgery and at the different follow-up appointments. The preoperative and postoperative values were compared and statistically analysed at different time intervals. RESULTS: Sixty-three patients were included in the study. The average age of the patients was 41.4 years (range 27-59 years). The mean follow-up was 44 months (range 36-71 months). Overall, total disc replacement (TDR) led to an increase in LL which increased TED over time. The preoperative LL measured 48.9° ± 10.1° and 53.4° ± 9.9° at 3 years follow-up (p < 0.0001). In the cohort of patients who underwent TDR at L4-5, the LL increased from 51.6° ± 10° to 56.2° ± 9.2° at the last FU (p = 0.006). All other spinopelvic parameters remained stable between the preoperative values and the last follow-up. In the patients who underwent L5-S1 TDR, a significant increase in LL was also observed between preoperative data and at the last FU (from 47.8° ± 10.1° to 53.3° ± 10.1°, p < 0.0001). Following L5-S1 TDR, the SS increased from 32.9° ± 8.3° to 35.6° ± 7.4° (p = 0.05) and the PT decreased from 15.4° ± 6.2° to 11.6° ± 5.7° between preoperative values and the last follow-up. Considering the entire cohort, the SL L5-S1 increased significantly from 5.9° ± 4.2° preoperatively to 8.1° ± 4.4° (p < 0.01) at the last FU, while at the L4-L5 level, the SL remained stable from 9.9 ± 4.5° to 10.7° ± 3.8° (p = 0.3). After L4-5 TDR, an increase in ADH and PDH at the treated level was observed, while these parameters progressively decreased in the adjacent segment. In patients who underwent L5-S1 TDR, a significant increase in L5-S1 ADH and PDH was observed from 18.8 ± 9.1 to 28.4 ± 11.1 and from 9.5 ± 3.8 to 17.6 ± 9.5 pixels, respectively. ADH and PDH at the proximal adjacent levels L3-4 and L4-5 were reduced. We did not observe any case of implant failure or damage to the bone/implant interface. CONCLUSION: TDR with Mobidisc allows for an improvement of LL and SL at the treated level. An increase in both anterior and posterior disc height was observed at the treated level. While disc height decreased at the adjacent level, further studies are required to investigate whether these changes are clinically relevant.

Comparison of open versus minimally invasive surgery in the treatment of thoracolumbar metastases.

INTRODUCTION: Minimally invasive surgery (MIS) techniques have been developed for the surgical treatment of thoracolumbar spinal metastases to reduce the morbidity associated with the operation. The purpose of our study was to compare the mean length of stay, change in pain levels, neurological symptoms, complications and survival after open versus MIS surgery. MATERIAL AND METHODS: This is a single-center retrospective study based on a register of patients treated for vertebral metastases between January 2014 and October 2016. The collection included demographic data, cancer-related data, clinical data, the characteristics of the surgery, the length of stay, assessment of pain and the occurrence of death. These data were compared between open and MIS surgery groups. RESULTS: Out of 59 patients, 35 were treated with open surgery and 24 were treated with MIS surgery. The two groups were comparable in terms of age, gender and body mass index. Breast, kidney, prostate and lung cancers were the most frequent primary tumors. Prognostic and instability scores were comparable. Short- and medium-term pain assessment showed comparable results. Median survival was 208 days in the open surgery group and 224days in the MIS group (p=0.5299). CONCLUSION: MIS techniques aim to limit the surgical approach and allow a faster introduction of adjuvant treatments than after open surgery. Our study did not find any differences between open and MIS surgery in terms of pain, neurological evolution or survival time in patients treated for thoracolumbar spinal metastases. LEVEL OF EVIDENCE: IV; retrospective study.

[Spine surgery in elderly: place and indication]. / Place et indication de la chirurgie du rachis du sujet âgé.

"Spine surgery in elderly: place and indication. The ageing affects every component of spine resulting in pain, balance disorders and loss of independence with acceleration of the general aging process. Surgery is possible facing to mechanical problems. Osteoporotic fractures can be cured by vertebroplasty. Opening vertebral canal is a common practice in stenosis, restoring a normal walk. Osteosynthesis of the spine is indicated in instability or in deformity and regularly used in metastasis. Disc arthroplasty can be discussed in uncodiscarthrosis. The progresses of anesthesiology and of the surgical techniques allow this practice. The patient operated gets up immediately generally without any brace. Minimal invasive surgery preserving soft tissues increases the indications. Spine surgery is too often forgotten by lack of diagnosis, in front of back pain, difficulty to walk and progressive deformity. We have to forget the terrible sentence: "There is nothing to be done because it is the spine, because the patient is too old."".

"Place et indication de la chirurgie du rachis du sujet âgé. Le vieillissement affecte toutes les composantes du rachis avec comme conséquence une douleur, une perte d'indépendance et une accélération du processus général de vieillissement. En face de ces problèmes mécaniques, la chirurgie est possible. Les fractures ostéoporotiques peuvent être traitées par vertébroplastie. L'ouverture du canal est une pratique courante dans les sténoses pour restaurer une marche normale. L'ostéosynthèse du rachis est proposée en cas d'instabilité ou de déformation, et est régulièrement utilisée dans les métastases. La prothèse discale peut être discutée dans les uncodiscarthroses. Les progrès de l'anesthésie et des techniques chirurgicales ont permis cette pratique. Le patient opéré se lève immédiatement, en règle générale sans contention externe. La chirurgie mini-invasive préservant les tissus mous augmente ces indications. Par manque de diagnostic, la chirurgie du rachis est trop souvent oubliée devant une douleur rachidienne, une difficulté à la marche ou une déformation progressive. Nous devons oublier cette terrible phrase : « Il n'y a rien à faire parce que c'est la colonne, parce que le patient est trop vieux. ¼".

Analysis of factors associated with sagittal alignment deterioration after correction of degenerative scoliosis by in situ contouring.

INTRODUCTION: In situ contouring is one of the surgical techniques used for scoliosis reduction. The initial correction could change over time, with deterioration of the sagittal balance. The purpose of this study was to analyze the loss of correction after degenerative lumbar scoliosis surgery using in situ contouring. MATERIALS AND METHODS: Full spine radiographs of 73 patients (mean age 63.3 years, mean follow-up 27 months) were analyzed before surgery, after surgery, and at the final follow-up. The following radiographic parameters were measured: C2-C7 lordosis, T4-T12 kyphosis, L1-S1 lordosis, pelvic tilt, pelvic incidence, sacral slope, SVA C7, SVA C2, Cobb angle. Bayesian inference was used to compare the changes in these parameters. A probability>0.95 was considered as a significant change. RESULTS: After surgery, lumbar lordosis increased from -28.4° to -37.8° (probability 0.999), then decreased to -32.1° at the final follow-up (probability 0.953). Thoracic kyphosis increased from 29.6° to 37.4° after surgery (probability 1.00) and continued to increase to 41.6° at the final follow-up (probability 0.999). SVA C7 increased from 38.5mm to 62.3mm (probability 0.999) and pelvic tilt from 19.4° to 25.1° (probability 1.00) during the follow-up period. Ten patients had to be reoperated because of a surgical site infection. Infection (14%) was associated with an increase of SVA C7 (probability 0.989) and thoracic kyphosis (probability 0.987). Nonunion (16%) was associated with a decrease in lumbar lordosis (probability 0.756). CONCLUSION: Correction of degenerative lumbar scoliosis by in situ contouring resulted in sagittal balance correction; however, some of this correction was lost during the follow-up period. The main risk factors were deep wound infection and nonunion. LEVEL OF EVIDENCE: IV, Retrospective study.

Comparison of degenerative lumbar scoliosis correction and risk for mechanical failure using posterior 2-rod instrumentation versus 4-rod instrumentation and interbody fusion.

PURPOSE: Four-rod instrumentation and interbody fusion may reduce mechanical complications in degenerative scoliosis surgery compared to 2-rod instrumentation. The purpose was to compare clinical results, sagittal alignment and mechanical complications with both techniques. METHODS: Full spine radiographs were analysed in 97 patients instrumented to the pelvis: 58 2-rod constructs (2R) and 39 4-rod constructs (4R). Clinical scores (VAS, ODI, SRS-22, EQ-5D-3L) were assessed preoperatively, at 3 months, 1 year and last follow-up (average 4.2 years). Radiographic measurements were: thoracic kyphosis, lumbar lordosis, spinopelvic parameters, segmental lordosis distribution. The incidence of non-union and PJK were investigated. RESULTS: All clinical scores improved significantly in both groups between preoperative and last follow-up. In the 2R-group, lumbar lordosis increased to 52.8° postoperatively and decreased to 47.0° at follow-up (p = 0.008). In the 4R-group, lumbar lordosis increased from 46.4 to 52.5° postoperatively and remained at 53.4° at follow-up. There were 8 (13.8%) PJK in the 2R-group versus 6 (15.4%) in the 4R-group, with a mismatch between lumbar apex and theoretic lumbar shape according to pelvic incidence. Non-union requiring revision surgery occurred on average at 26.9 months in 28 patients (48.3%) of the 2R-group. No rod fracture was diagnosed in the 4R-group. CONCLUSION: Multi-level interbody fusion combined with 4-rod instrumentation decreased risk for non-union and revision surgery compared to select interbody fusion and 2-rod instrumentation. The role of additional rods on load sharing still needs to be determined when multiple cages are used. Despite revision surgery in the 2R group, final clinical outcomes were similar in both groups. LEVEL OF EVIDENCE: III.

Revision Surgery of Total Lumbar Disk Replacement: Review of 48 Cases.

STUDY DESIGN: This was a retrospective clinical review. OBJECTIVE: The objective of this study was to analyze failure mechanisms after total lumbar disk replacement (TDR) and surgical revision strategies in patients with recurrent low back pain (LBP). SUMMARY AND BACKGROUND DATA: Several reports indicate that TDR revision surgery carries a major risk and that it should not be recommended. The clinical results of posterior instrumented fusion using the prosthesis like an interbody cage have not been well analyzed. MATERIALS AND METHODS: From 2003 to 2018, 48 patients with recurrent LBP after TDR underwent revision surgery. The average age was 39 years (24-61 y). The mean follow-up was 100.4 months (24.6-207.7 mo). Clinical data, self-assessment of patient satisfaction, and Oswestry Disability Index collected at each clinical control or by phone call for the older files and radiologic assessments were reviewed. The surgical revision strategy included posterior fusion in 41 patients (group A) and TDR removal and anterior fusion in 7 patients (group B), of which 6 patients had an additional posterior fixation. RESULTS: Facet joint osteoarthritis was associated with TDR failure in 85%. In 68% the position of the prosthesis was suboptimal. Range of motion was preserved in 25%, limited in extension in 65%, and limited in flexion in 40%. Limited range of motion and facet joint osteoarthritis were significantly related (P=0.0008). The complication rate in group B was 43% including iliac vein laceration. Preoperative and 2-year follow-up Oswestry Disability Index were 25.5 and 22.0, respectively, in group A versus 27.9 and 21.3 in group B. CONCLUSIONS: Posterior osteoarthritis was the principal cause of recurrent LBP in failed TDR. The anterior approach for revision carried a major vascular risk, whereas a simple posterior instrumented fusion leads to the same clinical results. LEVEL OF EVIDENCE: Level IV.

Thoracic Kyphosis and Lumbar Lordosis Distribution After Idiopathic Scoliosis Correction Using Posterior Hybrid Versus Screw Instrumentation.

STUDY DESIGN: This was a retrospective observational study. OBJECTIVE: The aim of this study was to evaluate kyphosis and lordosis distribution, inflexion points, and the relationship with proximal junctional kyphosis (PJK) comparing hybrid instrumentation (in situ contouring, derotation) versus screw instrumentation (thoracic cantilever reduction, lumbar in situ contouring, and derotation). SUMMARY OF BACKGROUND DATA: The combination of reduction techniques aims at restoring the levels of lumbar apex and thoracolumbar inflexion point according to Roussouly alignment types. This approach could minimize the PJK risk after adolescent idiopathic scoliosis (AIS) surgery. MATERIALS AND METHODS: The study assessed coronal curve correction, thoracolumbar and spinopelvic sagittal parameters in 86 skeletally mature adolescents and young adults 2.2 years after AIS correction, comparing a hybrid group (HG, n=34) to a screw group (SG, n=52). Segmental kyphosis and lordosis distribution, number of vertebrae included in curves, thoracic and lumbar apex, thoracolumbar inflexion point and Roussouly types were modeled using KEOPS software. RESULTS: Global coronal and sagittal correction were similar in both groups. In the SG, lumbar lordosis (LL) decreased from 61.1 to 53.9 degrees (P<0.0001) and matched with pelvic incidence (r=0.69), whereas LL did not change in the HG. Postoperatively, the thoracolumbar inflexion point migrated cranially, resulting in a longer LL in both groups. Postoperative thoracolumbar inflexion point (P<0.0001) and the lumbar apex (P=0.0274) were more caudal in the SG compared with the HG. The PJK rate was 14.7% in the HG and 7.7% in the SG. In patients with PJK, lumbar apex and thoracolumbar inflexion point shifted cranially and were too high according to the Roussouly type. CONCLUSIONS: Hybrid and screw instrumentation led to similar global AIS correction, but the use of cantilever reduction in the SG allowed setting the thoracolumbar inflexion point and the lumbar apex lower than in the HG. Cranial migration of these points was identified as PJK risk factor. LEVEL OF EVIDENCE: Level III.

Minimally Invasive Transforaminal Lumbar Interbody Fusion Using Augmented Reality Surgical Navigation for Percutaneous Pedicle Screw Placement.

STUDY DESIGN: This was a retrospective observational study. OBJECTIVE: The aim of this study was to evaluate the accuracy of percutaneous pedicle screw placement using augmented reality surgical navigation during minimally invasive transforaminal lumbar interbody fusion (TLIF). SUMMARY OF BACKGROUND DATA: Augmented reality-based navigation is a new type of computer-assisted navigation where video cameras are used instead of infrared cameras to track the operated patients and surgical instruments. This technology has not so far been clinically evaluated for percutaneous pedicle screw placement. MATERIALS AND METHODS: The study assessed percutaneous pedicle screw placement in 20 consecutive patients who underwent single-level minimally invasive TLIF using augmented reality surgical navigation. Facet joint violation and depression by the inserted pedicle screws were evaluated. Secondary outcome such as radiation dose exposure, fluoroscopy time, and operative time were collected for 3 phases of surgery: preparation phase, pedicle screw placement, and decompression with cage placement. RESULTS: A clinical accuracy for screw placement within the pedicle (Gertzbein 0 or 1) of 94% was achieved. One screw violated the facet joint with a transarticular pathway. The screw head did not depress the facet in 54%. The use of fluoroscopy during navigation correlated with patient body-mass index (r=0.68, P<0.0001). The pedicle screw placement time corresponded to 36±5% of the total operative time of 117±11 minutes. A statistically significant decrease of 10 minutes in operative time was observed between the first and last 10 procedures which corresponded to the pedicle screw placement time decrease (48±9 vs. 38±7 min, P=0.0142). The learning curve model suggests an ultimate operative time decrease to 97 minutes. CONCLUSION: Augmented reality surgical navigation can be clinically used to place percutaneous screws during minimally invasive TLIF. However, the lack of tracking of the location of the device requires intraoperative fluoroscopy to monitor screw insertion depth especially in obese patients. LEVEL OF EVIDENCE: Level III.

Analysis of intervertebral discs adjacent to thoracolumbar A3 fractures treated by percutaneous instrumentation and kyphoplasty.

INTRODUCTION: Percutaneous instrumentation and kyphoplasty can be used to treat A3 fractures at T12-L1. However, the effect on adjacent intervertebral discs remains controversial. The purpose of this retrospective study was to analyze the degeneration of the discs adjacent to the fracture and to determine its relationship with age, vertebral body deformity and clinical scores. MATERIALS AND METHODS: Twenty-nine patients (11 females, 18 males; average age 47 years, 27-63 years) were examined at 2.2 years' follow-up (2.0-2.5). Radiographic measurements were taken preoperatively, postoperatively, at follow-up: regional and local kyphosis, sagittal index, vertebral body compression ratio, and disc height index. The Pfirrmann grade was determined on an MRI taken at the final assessment. Clinical scores were the pain level (VAS), EQ-5D-3L, and ODI. The relationships between Pfirrmann grades, age and radiographic parameters were analyzed. RESULTS: Local kyphosis decreased from 12.4° to 7.3° postoperatively (p<0.0001), increased to 8.4° after instrumentation removal (p=0.139) and remained stable at the last follow-up (p=0.891). The sagittal index decreased from 12.3° to 7.3° postoperatively (p<0.0001) increased to 8.3° before the instrumentation was removed (p=0.764) and increased to 10.6° (p<0.05) at the last follow-up. The vertebral body compression ratio decreased from 23% to 14% postoperatively (p<0.0001) and remained stable at 17% at the last follow-up (p=0.310). The cranial disc height index was 32% preoperatively, 31% postoperatively (p=0.073), 29% at 1year (p=0.650), and decreased again to 23% at 2 years (p<0.0001). There was a significant relationship between disc degeneration and age (p=0.015), local kyphosis (p=0.008) and vertebral body compression ratio (p=0.002). The disc adjacent to the fracture was more likely to have a higher Pfirrmann grade than the control disc above it (OR=269.5). At the final assessment, the average pain level was 2.3, the EQ-5D-3L was 0.862, and the ODI was 11.8%. There was no significant relationship between the Pfirrmann grades and the clinical scores. CONCLUSION: The risk for cranial disc degeneration after percutaneous instrumentation and kyphoplasty of A3 fractures is low. The height of the cranial disc decreased after the instrumentation was removed. The risk for disc degeneration is related to age and vertebral body deformity. Disc degeneration does not appear to impact quality of life.

Combined percutaneous and open instrumentation for thoracolumbar kyphosis correction by two-level pedicle subtraction osteotomy in ankylosing spondylitis.

BACKGROUND: A long global thoracolumbar kyphosis is common in ankylosing spondylitis. Surgical correction of fixed sagittal malalignment by pedicle subtraction osteotomy (PSO) might improve disability and quality of life (QoL). Two-level osteotomies represent major procedures with a risk of hemorrhage. Combined open and minimal invasive surgery has not been described and might be considered. CASE PRESENTATION: A 30-year-old female with ankylosing spondylitis was treated by golimumab and teriparatide. The treatment was stopped during pregnancy which led to vertebral compression fractures and kyphosis of 50° between T11 and L3. A PSO was planned at the kyphotic apex L2. The second PSO was planned at L4 according to the pelvic incidence of 56°, matching with a spinopelvic alignment Roussouly type 3. A derived full balance integrated method was used to calculate the amount of correction. During the first stage surgery, an open approach was performed from L1 to pelvis and combined with percutaneous cement-augmented instrumentation in already fused segments T5-T12, thus reducing perioperative morbidity. A stepwise approach including L2 PSO closure with temporary rods and L4 PSO with final instrumentation was used. Blood loss was estimated around 1100 ml. The patient was able to walk on the second day after surgery. A secondary anterior fusion with LLI cages from L2 to L5 and an ALIF at L5-S1 were performed because of high non-ossified intervertebral disks to reduce the risk for nonunion and rod fractures. At 2-year follow-up, the patient's QoL had significantly improved and full spine radiographs showed stable normalized sagittal parameters. CONCLUSION: The combined open and percutaneous approach was feasible and might be considered as an alternative option to conventional open surgery when planning major deformity correction in ankylosing spondylitis.

Augmented reality and artificial intelligence-based navigation during percutaneous vertebroplasty: a pilot randomised clinical trial.

PURPOSE: To assess technical feasibility, accuracy, safety and patient radiation exposure of a novel navigational tool integrating augmented reality (AR) and artificial intelligence (AI), during percutaneous vertebroplasty of patients with vertebral compression fractures (VCFs). MATERIAL AND METHODS: This prospective parallel randomised open trial compared the trans-pedicular access phase of percutaneous vertebroplasty across two groups of 10 patients, electronically randomised, with symptomatic single-level VCFs. Trocar insertion was performed using AR/AI-guidance with motion compensation in Group A, and standard fluoroscopy in Group B. The primary endpoint was technical feasibility in Group A. Secondary outcomes included the comparison of Groups A and B in terms of accuracy of trocar placement (distance between planned/actual trajectory on sagittal/coronal fluoroscopic images); complications; time for trocar deployment; and radiation dose/fluoroscopy time. RESULTS: Technical feasibility in Group A was 100%. Accuracy in Group A was 1.68 ± 0.25 mm (skin entry point), and 1.02 ± 0.26 mm (trocar tip) in the sagittal plane, and 1.88 ± 0.28 mm (skin entry point) and 0.86 ± 0.17 mm (trocar tip) in the coronal plane, without any significant difference compared to Group B (p > 0.05). No complications were observed in the entire population. Time for trocar deployment was significantly longer in Group A (642 ± 210 s) than in Group B (336 ± 60 s; p = 0.001). Dose-area product and fluoroscopy time were significantly lower in Group A (182.6 ± 106.7 mGy cm2 and 5.2 ± 2.6 s) than in Group B (367.8 ± 184.7 mGy cm2 and 10.4 ± 4.1 s; p = 0.025 and 0.005), respectively. CONCLUSION: AR/AI-guided percutaneous vertebroplasty appears feasible, accurate and safe, and facilitates lower patient radiation exposure compared to standard fluoroscopic guidance. These slides can be retrieved under Electronic Supplementary Material.

Safety and efficacy of percutaneous instrumentation combined with antibiotic treatment in spondylodiscitis.

BACKGROUND: Patients with spondylodiscitis are treated with antibiotics and braces for 6 to 12 weeks. Braces aim to decrease pain and prevent kyphotic deformity due to vertebral body collapse. Percutaneous instrumentation could be an alternative to influence pain and patient's autonomy. PURPOSE: The purpose of this study was to analyze back pain, quality of life, sagittal deformity, and complications after percutaneous instrumentation in spondylodiscitis. PATIENTS AND METHODS: VAS for back pain, EQ-5D, radiographic sagittal index were assessed retrospectively for 28 patients who had a standardized follow-up at 5 days, 6 weeks, 3 months, 1 and 2 years. Probabilities>0.95 indicated significant changes (Bayesian model). RESULTS: VAS was 7.0 preoperatively, 3.2 (day 5), 2.2 (6 weeks), 1.9 (3 months), 1.6 (1 year), 1.4 (2 years): probabilities>0.95 within 6 weeks. EQ-5D was 0.229 preoperatively, 0.563 (6 weeks), 0.687 (3 months), 0.755 (1 year), 0.787 (2 years): probabilities>0.95 within 1 year. Sagittal index was 15.1° preoperatively, 9.6° postoperatively: probability>0.95. Inter-body fusion was: complete 60.7%, partial 17.9%, and nonunion 21.4%. Antibiotic treatment was stopped at 6 weeks in 82.1%, at 3 months in 17.9%, without septic complication. CONCLUSION: Percutaneous instrumentation improved pain control, quality of life and prevented kyphosis. Antibiotic treatment was not influenced. Septic complications were not observed. LEVEL OF EVIDENCE: IV.

Lower lumbar vertebra size and anatomic variation: An Anatomo-Radiologic Study.

INTRODUCTION: In routine practice, it is often necessary to use shorter screws in L5 than L4. The present study measured L5 versus L4 vertebral pedicles, to guide surgical strategy. MATERIAL AND METHOD: CT or MRI scans for 95 patients were analyzed. Radiographic measurements (anteroposterior diameter (APD), pedicle length (PL) and pedicle width (PW)) were taken by a spine surgeon. Statistical analysis used R 3.4.3 software. RESULTS: Ninety-five patients were included: 48 female (50.53%), 47 male (49.47%); mean age, 57 years (range, 19-85 years). Univariate analysis found a strong correlation between right and left PL values in L4 and L5. Right and left values were pooled, obtaining a mean L4 PL of 55.34mm (range, 54.23-56.45mm) and L5 PL of 51.80mm (44.81-58.80) and L4 PW of 10.48mm (10.06-10.91) and L5 PW of 9.90mm (7.43-12.39). Multivariate analysis disclosed significant effects of age and gender, with greater age and male gender associated with greater anteroposterior vertebral diameter. Mean anteroposterior vertebral length was significantly shorter in L5 than L4 by 3.57mm (range, 4.08-3.06mm). DISCUSSION: Anteroposterior pedicle length was shorter in L5 than L4, in line with the literature. This answers the surgeon's question: "Should pedicle screws be shorter in L5 than L4?". From these results, it seems logical to use an L5 screw that is 5mm shorter than in L4, to secure good intra-body screw fixation.

rhBMP-2 (Recombinant Human Bone Morphogenetic Protein-2) in real world spine surgery. A phase IV, National, multicentre, retrospective study collecting data from patient medical files in French spinal centres.

BACKGROUND: This is a Phase IV, national, multicentre, retrospective study to observe the real-world use of rhBMP-2 in France. HYPOTHESIS: There was no statistical hypothesis, the statistical analyses were descriptive in nature. PATIENTS AND METHODS: Data was collected from patient medical files in 10 French spinal centres. Primary objectives were to understand which patients were treated with rhBMP-2, commercialised in Europe as InductOs™ and how rhBMP-2 was used during spinal fusion surgery in France between 2011 and 2012. RESULTS: Four hundred patients (634 levels) treated with rhBMP-2 were included in the analysis. The most frequent primary diagnostic indication for rhBMP-2 use was degenerative disc disease (DDD; 129/400; 32.3% of patients) followed by spondylolisthesis (119/400; 29.8%), deformity (59/400; 14.8%) and pseudoarthrosis (29/400; 7.3%). The most frequently treated level was L4-L5 (33.8% of levels in 53.5% of patients); followed by L5-S1 (29.8%, 47.3%), L3-L4 (16.7%, 26.5%), and L2-L3 (7.3%, 11.5%), all other levels (less than 5% of patients). No interbody fusion device was used in 42.7% of levels. Wetted matrix of rhBMP-2 was placed in the interbody space in 58.4% of levels (370/634). The most common procedure for rhBMP-2 treatment was posterior lumbar fusion (PLF) (221/634; 34.9% of levels), followed by anterior lumbar interbody fusion (ALIF) (188/634; 29.7%), posterior lumbar interbody fusion (PLIF) (111/634; 17.5%), lateral lumbar interbody fusion (LLIF) (106/634; 16.7%), transforaminal lumbar interbody fusion (TLIF) (4/634; 0.6%) and 'other' (4/634; 0.6%). Thirty-one adverse events of Interest (AEI) were recorded in 27 patients. One AEI was considered related to rhBMP-2. Unplanned secondary spine interventions at index level treated with rhBMP-2 were required in 4 patients. DISCUSSION: In years 2011 and 2012 when the surgeries captured in this retrospective study were done, rhBMP-2 was indicated for single level (L4-S1) anterior lumbar spine fusion as a substitute for autogenous bone graft in adults with DDD. The most common procedure for the treatment with rhBMP-2 was PLF (off-label use), followed by ALIF (on-label use). The safety findings confirm a predictable and manageable safety profile. LEVEL OF EVIDENCE: IV.

Osteoarthritis and spontaneous fusion of facet joints after percutaneous instrumentation in thoracolumbar fractures.

PURPOSE: This retrospective study determined the rate of osteoarthritis and spontaneous facet joint fusion and analyzed risk factors related to patient characteristics, fracture type or surgical technique on pre- and postoperative CT after percutaneous instrumentation in thoracolumbar fractures. METHODS: 1050 facet joints adjacent to screws in 148 patients (15-85 years) with thoracolumbar fractures were analyzed with an average time between CTs of 12.3 months. Screw diameters, lengths and cement augmentation were recorded. Facet joint violation by screw trajectory and by insertion depth was classified in three grades. Pre- and postoperative osteoarthritis was graded as absent, minor or severe and postoperative facet joint fusion as absent, partial or complete. RESULTS: The facet violation rate was moderate in 15.4% and severe in 0.6% according to screw trajectory, and 11.0 and 0.6%, respectively, according to insertion depth. Osteoarthritis was preoperatively rated moderate in 9.6% and severe in 1.2%. A progression was evidenced in 79 facet joints (7.5%). Screw cement augmentation was the main predictive factor (p < 0.0001). Partial fusion was evidenced in 2.6% and complete fusion in 1% of facet joints. Risk factors were: BMI (p = 0.0002), age (p = 0.0013), preoperative osteoarthritis (p = 0.0005), time between 2 CTs (p = 0.0001), B-type fractures (p = 0.0005), concomitant anterior fusion (p = 0.0034). CONCLUSIONS: Occurrence or worsening of osteoarthritis was mainly observed in elderly patients with cement-augmented screws and spontaneous facet fusion in elderly patients with high BMI and preoperative osteoarthritis, or in anteriorly fused B-type injuries. Thus, percutaneous instrumentation can safely be removed after fracture consolidation in younger patients while preserving facet joints.

Possible factors associated with sagittal malalignment recurrence after pedicle subtraction osteotomy.

PURPOSE: This retrospective study investigates sagittal alignment after pedicle subtraction osteotomy (PSO). The purpose was to investigate factors associated with malalignment recurrence. METHODS: Full spine radiographs were analyzed in 66 patients (average age 54.5 years, follow-up 3.8 years). Measurements were taken preoperatively, 3 months postoperatively, at follow-up: SVA C2 and C7, C2-C7 lordosis, T4-T12 kyphosis, L1-S1 lordosis, PSO lordosis, pelvic incidence, pelvic tilt, sacral slope. Follow-up CTs were screened for pseudarthrosis and gas in sacroiliac joints. RESULTS: PSO lordosis increased from 11.8° to 40.8° (p < 0.0001) and kept stable. Lumbar lordosis increased from 28.6° to 57.7° (p < 0.0001) and decreased to 49.7° (p = 0.0008). Pelvic tilt decreased from 29.2° to 16.5° (p < 0.0001) and increased to 22.5° (p < 0.0001). SVA C7 decreased from 105.1 to 35.5 mm (p < 0.0001) and increased to 64.8 mm (p = 0.0005). Twenty-eight patients (42%) had an SVA C7 increase of more than 70 mm in the postoperative course: recurrence group. These patients were older: 62.8 years versus 52.3 years (p = 0.0031). Loss of lordosis was 11.9° (recurrence group) versus 5.0° (non-recurrence group). Eleven patients (17%) had pseudarthrosis. Pelvic incidence increased by 9.3° (recurrence group) versus 3.8° (non-recurrence group). In 23 patients (35%), pelvic incidence increased > 10°. Gas was evidenced in sacroiliac joints in 22 patients (33%). CONCLUSION: Postoperative anterior malalignment recurrence may occur after PSO. Elderly patients were at risk of recurrence. Loss of lumbar lordosis linked to pseudarthrosis represented another factor. With malalignment recurrence, anterior trunk rotation and pelvic retroversion might additionally have augmented moments across sacroiliac joints with subsequent ligament laxity and pelvic incidence increase. These slides can be retrieved under Electronic Supplementary Material.

Incidence and Risk Factors for Proximal Junctional Kyphosis: Results of a Multicentric Study of Adult Scoliosis.

STUDY DESIGN: This was a retrospective multicentric study. OBJECTIVE: The objective of this study was to determine the different risk factors for development of proximal junctional kyphosis (PJK) in patients with adult scoliosis. SUMMARY OF BACKGROUND DATA: This study was conducted as the reasons for development of PJK in adult scoliosis are still not clear. MATERIALS AND METHODS: In total, 314 patients met the inclusion criteria. The main outcome measure was the PJK, as described by Glattes and colleagues. Extent of the instrumentation, operative time, bleeding, and the use of an osteotomy as well as the type of proximal anchorage were collected. Radiologic variables included preoperative Cobb angles of the lumbar and the thoracic curvatures, pelvic parameters, lumbar lordosis, thoracic kyphosis, and sagittal vertical axis. All measures were performed using the KEOPS software. RESULTS: The mean follow-up of this series was 2.5 years with a female to male ratio of 6.6/1 and a mean age of 56.66 years. The incidence of PJK was 25%. Proximal fixation extended to the proximal thoracic spine (TS) in 39%, to the middle TS in 39.5% of cases, and to the thoracolumbar junction in 20.4%, with a higher incidence of PJK noted in the first group. The proximal anchors had no effect on PJK incidence. Age as well as body mass index had a positive correlation to the incidence of PJK. The association, fusion to sacrum and fusion to the upper TS, is associated with the highest incidence of PJK. Preoperative pelvic tilt had a positive correlation with PJK occurrence. Finally, revision for PJK occurred in 2.3% of all patients and accounted for 15% of revisions. CONCLUSIONS: Increased age, as well as increased body mass index, is a risk factor for the development of PJK. The proximal extent of the construct is also shown to be a risk factor for PJK, but fusion to the sacrum is a risk factor only if fusion extends to the proximal TS. Moderate PJK was observed with undercorrection of the sagittal balance and severe PJKs with overcorrection of the sagittal balance. LEVEL OF EVIDENCE: Level IV.

Open versus percutaneous instrumentation in thoracolumbar fractures: magnetic resonance imaging comparison of paravertebral muscles after implant removal.

OBJECTIVE Percutaneous instrumentation in thoracolumbar fractures is intended to decrease paravertebral muscle damage by avoiding dissection. The aim of this study was to compare muscles at instrumented levels in patients who were treated by open or percutaneous surgery. METHODS Twenty-seven patients underwent open instrumentation, and 65 were treated percutaneously. A standardized MRI protocol using axial T1-weighted sequences was performed at a minimum 1-year follow-up after implant removal. Two independent observers measured cross-sectional areas (CSAs, in cm2) and region of interest (ROI) signal intensity (in pixels) of paravertebral muscles by using OsiriX at the fracture level, and at cranial and caudal instrumented pedicle levels. An interobserver comparison was made using the Bland-Altman method. Reference ROI muscle was assessed in the psoas and ROI fat subcutaneously. The ratio ROI-CSA/ROI-fat was compared for patients treated with open versus percutaneous procedures by using a linear mixed model. A linear regression analyzed additional factors: age, sex, body mass index (BMI), Pfirrmann grade of adjacent discs, and duration of instrumentation in situ. RESULTS The interobserver agreement was good for all CSAs. The average CSA for the entire spine was 15.7 cm2 in the open surgery group and 18.5 cm2 in the percutaneous group (p = 0.0234). The average ROI-fat and ROI-muscle signal intensities were comparable: 497.1 versus 483.9 pixels for ROI-fat and 120.4 versus 111.7 pixels for ROI-muscle in open versus percutaneous groups. The ROI-CSA varied between 154 and 226 for open, and between 154 and 195 for percutaneous procedures, depending on instrumented levels. A significant difference of the ROI-CSA/ROI-fat ratio (0.4 vs 0.3) was present at fracture levels T12-L1 (p = 0.0329) and at adjacent cranial (p = 0.0139) and caudal (p = 0.0100) instrumented levels. Differences were not significant at thoracic levels. When adjusting based on age, BMI, and Pfirrmann grade, a significant difference between open and percutaneous procedures regarding the ROI-CSA/ROI-fat ratio was present in the lumbar spine (p < 0.01). Sex and duration of instrumentation had no significant influence. CONCLUSIONS Percutaneous instrumentation decreased muscle atrophy compared with open surgery. The MRI signal differences for T-12 and L-1 fractures indicated less fat infiltration within CSAs in patients who received percutaneous treatment. Differences were not evidenced at thoracic levels, where CSAs were smaller. Fat infiltration was not significantly different at lumbar levels with either procedure in elderly patients with associated discopathy and higher BMI. In younger patients, there was less fat infiltration of lumbar paravertebral muscles with percutaneous procedures.